Simpified version of MQTT over UDP: Network is broker!
See Russian version / Русская версия здесь
MQTT is a cute simple protocol well suited for IoT and similar things.
But it can be even simpler and still be very usable: MQTT/UDP is merely an MQTT Publish packets broadcast over an UDP.
- Extremely simple
- Extremely fast, minimal possible latency
- Excludes broker (which is single point of failure)
- Lowers network traffic (each masurement is sent exactly once to all)
- Reasonably reliable (if we use it for sensors, which usually resend data every few seconds or so)
- Can be supported even on a hardware which can not support TCP - in fact, only UDP send is required
- Zero configuration - a sensor node needs no setup, it just broadcasts its data. (And, if you still need it, MQTT/UDP supports remote configuration over network.)
- Supports digital signature
- A simple MQTT/UDP implementation in some popular programming languages.
- A simplest MQTT to MQTT/UDP bridge implementation in Pyton.
- A tool to send data from MQTT/UDP to OpenHAB
- A debug application to dump MQTT/UDP traffic (tools/viewer).
- Other tools and utilities
Feel free to:
- Add implementation in your favorite programming language
- Write a bridge to classic MQTT protocol (we have very simple one here written in Python)
- Extend your favorite MQTT broker or IoT system (OpenHAB?) with MQTT/UDP support
- Check MQTT/UDP specification/implementation against MQTT spec. We must be compatible where possible.
It is really easy.
- You need to transfer long payloads. On some systems size of UDP datagram is limited.
- You need to know if datagram was delivered for sure. It is impossible with UDP. Though, reliable delivery subsystem is being in development now and will be available soon.
- It seems to be reasonable to add some kind of signature to packets to prevent data spoofing. Actually, it is already done for Java implementation, C and Pythin will come soon.
- Broadcast is not the best way to transmit data. Multicast is much better. Though multicast is not so well supported in IoT OS's or monitors.
- Clone repository to local disk
- Read HOWTO file
This repository contains tools to support MQTT/UDP integration and test:
- GUI tool to show current state of data transmitted in tools/viewer directory; see also viewer help page.
- Random data generator (random_to_udp.py) in python3/examples directory
- Send/check tool for sequentially numbered packets. See seq_storm_send.py and seq_storm_check.py in lang/python3/examples directory
- WireShark dissector to see protocol data on the network in lang/lua/wireshark directory
Send data:
import mqttudp.engine
if __name__ == "__main__":
mqttudp.engine.send_publish( "test_topic", "Hello, world!" )Listen for data:
import mqttudp.engine
def recv_packet(ptype,topic,value,pflags,addr):
if ptype != "publish":
print( ptype + ", " + topic + "\t\t" + str(addr) )
return
print( topic+"="+value+ "\t\t" + str(addr) )
if __name__ == "__main__":
mqttudp.engine.listen(recv_packet)Download pypi package
Send data:
PublishPacket pkt = new PublishPacket(topic, value);
pkt.send();Listen for data:
PacketSourceServer ss = new PacketSourceServer();
ss.setSink( pkt -> { System.out.println("Got packet: "+pkt); });Download JAR
Send data:
int rc = mqtt_udp_send_publish( topic, value );Listen for data:
int main(int argc, char *argv[])
{
...
int rc = mqtt_udp_recv_loop( mqtt_udp_dump_any_pkt );
...
}
int mqtt_udp_dump_any_pkt( struct mqtt_udp_pkt *o )
{
printf( "pkt %x flags %x, id %d",
o->ptype, o->pflags, o->pkt_id
);
if( o->topic_len > 0 )
printf(" topic '%s'", o->topic );
if( o->value_len > 0 )
printf(" = '%s'", o->value );
printf( "\n");
}
Send data:
local mq = require "mqtt_udp_lib"
mq.publish( topic, val );
Listen for data:
local mq = require "mqtt_udp_lib"
local listener = function( ptype, topic, value, ip, port )
print("'"..topic.."' = '"..val.."'".." from: ", ip, port)
end
mq.listen( listener )Download LuaRock
There is a Go language implementation, see lang/go for details